In the manufacture of sweetened ready-to-eat cereals, sweet coatings are commonly applied to a cereal base material, especially coatings containing the sugar sucrose.
Although sucrose has excellent organoleptic properties in cereal coating applications, it is well known that the large amounts of sucrose consumed in the typical American's diet contributes to obesity and dental caries. A recognition of this fact among consumers had led to intensive efforts in the food industry to find sweeteners to replace sucrose in many food products. One of the most successful approaches has been to replace sucrose with dipeptide sweeteners, especially sweeteners based on the amino acid L-aspartic acid. The most commercially successful of this group has been L-aspartyl-L-phenylalanine methyl ester, also known as aspartame, a sweetener approximately 200 times as sweet as sucrose and which has similar sweetness characteristics.
Incorporation of dipeptide sweeteners in food coatings is not, however, a matter of simple replacement of sucrose. Characteristic differences between dipeptide sweeteners and sucrose include reduced bulk due to its high sweetening power, instability of the sweetener molecule when incorporated in many foods and its high cost. In particular, aspartame is known to be unstable in the presence of moisture--hydrolysis of the dipeptide bond, hydrolysis of the methyl ester group and/or cyclization to diketopiperazine can occur; all of which destroy the sweetness of the aspartame molecule. Further, since aspartame is an aspartic acid based dipeptide, it has a free amine group available for browning reactions with the reducing sugars present in many foods--reactions which can proceed during storage and processing to reduce the sweetness and change the flavor of the food product.
In many known methods, dipeptide sweeteners are applied in aqueous suspension or solution to the surface of a ready-to-eat cereal in combination with other bulking or texture modifying ingredients such as dextrins or vegetable protein. These coating methods have a number of disadvantages. First, the dipeptide sweetener is unstable in the coating solution due to the presence of moisture, requiring the use of an excess of aspartame to produce the desired sweetness in the product and increasing the cost of the product. Second, during processing and long term storage of the product the dipeptide sweetener is available to react with reducing sugars present in the ready-to-eat cereal base or in the coating itself. Third, a large amount of water is required in an aqueous coating solution due to the low solubility of the dipeptide sweetener in water; excess water that can cause a collapse or shrinkage of the ready-to-eat cereal base. Fourth, the large amount of water required in the aqueous coating solution will usually require intensive drying of the coated ready-to-eat cereal product, thereby increasing its cost of manufacture. Finally, applying the dipeptide sweetener in aqueous solution can cause absorption of the sweetener into the ready-to-eat cereal base, thereby reducing the sensation of sweetness of the coated ready-to-eat cereal when it is tasted.
It is therefore an object of the present invention to provide a method for making a sweet, coated ready-to-eat cereal in which the dipeptide sweetener is stable during application.
It is also an object of the present invention to provide a method for making a sweet, coated ready-to-eat cereal in which the application of the sweetener does not cause a collapse or shrinkage of the ready-to-eat cereal.
It is also an object of the present invention to provide a method for making a sweet, coated ready-to-eat cereal which does not require costly drying of the coated ready-to-eat cereal following coating application.
It is also an object of the present invention to provide a sweet coated ready-to-eat cereal in which the dipeptide sweetener remains stable when in contact with a ready-to-eat cereal base containing reducing sugars.
It is also an object of the present invention to provide a sweet, coated ready-to-eat cereal which has a long unrefrigerated shelf life.
It is also an object of the present invention to provide a dipeptide sweetened, coated ready-to-eat cereal with a strong sensation of sweetness when tasted.